1. Field of the Invention
The present invention is directed generally to medical tables and more particularly to the control circuitry for such tables.
Tables, such as surgical, tables can be oriented in a variety of positions. For example, a surgical table may be oriented in a Trendelenberg (head down, feet up), reverse Trendelenberg (head up, feet down), flex (head down, midsection up, feet down) and reflex (head up, midsection down, feet up) positions. In addition to those positions, it is desirable to be able to raise and lower the patient's legs, raise and lower the patient's back, tilt the table to the left or right, and to raise and lower the entire table. In addition, some tables are equipped with floor locks which must be locked before various functions can be performed. To provide a table capable of assuming all those positions and performing all of those functions while maintaining the table within acceptable size and weight constraints several manufacturers have turned to the use of microprocessors. An appropriately programmed microprocessor can handle all of the functions which the table is required to perform while eliminating bulky relays and switches.
One problem which has been encountered in adapting medical tables to microprocessor control is electromagnetic interference. In the environment of an operating room, dozens of pieces of electrical equipment, from lighting to monitors, are crammed into a small area. It has been discovered that electromagnetic interference generated by certain of such equipment causes the microprocessors used in surgical tables to malfunction, which is an unacceptable situation. Therefore, the need exists for control circuitry which provides the surgeon with the ability to override the normal microprocessor controls in a surgical table in the event of microprocessor malfunction.